<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/sign" method="post">
    用户名：<input type="text" name="username"/><br><br>
    密码：<input type="password" name="pass"/><br><br>
    用户id：<input type="text" name="userid"/>
    <input type="submit" value="提交">
</form>
</body>
</html>